LTC1655
16-Bit Rail-to-Rail
Micropower DAC in
SO-8 Package
FEATURES
s
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DESCRIPTIO
16-Bit Monotonicity Over Temperature
Deglitched Rail-to-Rail Voltage Output
SO-8 Package
5V Single Supply Operation
I
CC(TYP)
: 600µA
Internal Reference
Maximum DNL Error: 1LSB
Power-On Reset
3-Wire Cascadable Serial Interface
Low Cost
The LTC
®
1655 is a rail-to-rail voltage output, 16-bit digi-
tal-to-analog converter (DAC) in an SO-8 package. It
includes an output buffer and a reference. The 3-wire serial
interface is compatible with SPI/QSPI and MICROWIRE
TM
protocols. The CLK input has a Schmitt trigger that allows
direct optocoupler interface.
The LTC1655 has an onboard 2.048V reference that can be
overdriven to a higher voltage. The output swings from 0V
to 4.096V when using the internal reference. The typical
power dissipation is 3.0mW on a single 5V supply.
The LTC1655 is pin compatible with Linear Technology’s
12-bit V
OUT
DAC family, allowing an easy upgrade path.
It is the only buffered 16-bit DAC in an SO-8 package and
it includes an onboard reference for stand alone
performance.
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
APPLICATIO S
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Digital Calibration
Industrial Process Control
Automatic Test Equipment
Cellular Telephones
TYPICAL APPLICATIO
Functional Block Diagram: 16-Bit Rail-to-Rail DAC
4.5V TO 5.5V
8
V
CC
2 D
IN
1 CLK
µP
3 CS/LD
16-BIT
SHIFT
REG
AND
DAC
LATCH
16
16-BIT
DAC
REF
2.048V
6
REF
DNL ERROR (LSB)
+
–
V
OUT
7
RAIL-TO-RAIL
VOLTAGE
OUTPUT
(0V TO 4.096V)
4 D
OUT
POWER-ON
RESET
GND
5
1655 TA01
TO
OTHER
DACS
U
Differential Nonlinearity
vs Input Code
1.0
0.8
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
– 1.0
0
16384
32768
CODE
49152
65535
1655 TA02
U
U
1
LTC1655
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CLK 1
D
IN
2
CS/LD 3
D
OUT
4
N8 PACKAGE
8-LEAD PDIP
8
7
6
5
V
CC
V
OUT
REF
GND
V
CC
to GND .............................................. – 0.5V to 7.5V
TTL Input Voltage .................................... – 0.5V to 7.5V
V
OUT
, REF
....................................... – 0.5V to V
CC
+ 0.5V
Maximum Junction Temperature ......................... 125°C
Operating Temperature Range
LTC1655C .............................................. 0°C to 70°C
LTC1655I........................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1655CN8
LTC1655IN8
LTC1655CS8
LTC1655IS8
S8 PART MARKING
1655
1655I
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 100°C/W (N8)
T
JMAX
= 125°C,
θ
JA
= 150°C/W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
CC
= 4.5V to 5.5V, V
OUT
unloaded, REF unloaded, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
SYMBOL
DAC
Resolution
Monotonicity
DNL
INL
ZSE
V
OS
V
OS
TC
Differential Nonlinearity
Integral Nonlinearity
Zero Scale Error
Offset Error
Offset Error Tempco
Gain Error
Gain Error Drift
Power Supply
V
CC
I
CC
Positive Supply Voltage
Supply Current
Short-Circuit Current Low
Short-Circuit Current High
Output Impedance to GND
Output Line Regulation
AC Performance
Voltage Output Slew Rate
Voltage Output Settling Time
Digital Feedthrough
Midscale Glitch Impulse
DAC Switch Between 8000 and 7FFF
(Note 3)
(Note 3) to 0.0015% (16-Bit Settling Time)
(Note 3) to 0.012% (13-Bit Settling Time)
q
q
q
PARAMETER
CONDITIONS
MIN
16
16
TYP
MAX
UNITS
Bits
Bits
Guaranteed Monotonic (Note 2)
REF = 2.2V (External) (Note 2)
Measured at Code 200, REF = 2.2V (External)
REF = 2.2V (External)
q
q
q
q
±0.3
±8
0
±0.5
±5
±5
0.5
±1.0
±20
3
±3
±16
µV/°C
LSB
ppm/°C
5.5
V
µA
mA
mA
Ω
mV/V
q
For Specified Performance
4.5V
≤
V
CC
≤
5.5V (Note 4)
V
OUT
Shorted to GND
V
OUT
Shorted to V
CC
Input Code = 0
Input Code = 65535, V
CC
= 4.5V to 5.5V,
with Internal Reference
q
q
4.5
600
70
80
40
1200
120
140
120
±3
Op Amp DC Performance
q
q
q
q
±0.3
±0.7
20
10
0.3
12
2
U
LSB
LSB
mV
mV
V/µs
µs
µs
nV -s
nV-s
W
U
U
W W
W
LTC1655
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
CC
= 4.5V to 5.5V, V
OUT
unloaded, REF unloaded, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
SYMBOL
Digital I/O
V
IH
V
IL
V
OH
V
OL
I
LEAK
C
IN
Switching
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
D
IN
Valid to CLK Setup
D
IN
Valid to CLK Hold
CLK High Time
CLK Low Time
CS/LD Pulse Width
LSB CLK to CS/LD
CS/LD Low to CLK
D
OUT
Output Delay
CLK Low to CS/LD Low
Reference Output Voltage
Reference Input Range
Reference Output Tempco
Reference Input Resistance
Reference Short-Circuit Current
Reference Output Line Regulation
Reference Load Regulation
V
CC
= 4.5V to 5.5V
I
OUT
= 100µA
REF Overdriven to 2.2V
q
q
q
q
PARAMETER
Digital Input High Voltage
Digital Input Low Voltage
Digital Output High Voltage
Digital Output Low Voltage
Digital Input Leakage
Digital Input Capacitance
CONDITIONS
q
q
MIN
2.4
TYP
MAX
UNITS
V
0.8
V
CC
– 1
0.4
±10
10
V
V
V
µA
pF
ns
ns
ns
ns
ns
ns
ns
I
OUT
= – 1mA, D
OUT
Only
I
OUT
= 1mA, D
OUT
Only
V
IN
= GND to V
CC
(Note 6)
V
CC
= 5V
V
CC
= 5V
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V, C
LOAD
= 15pF
V
CC
= 5V (Note 6)
q
q
q
q
q
q
q
q
q
q
q
q
40
0
40
40
50
40
20
0
20
2.036
2.2
5
8.5
13
40
100
±1.5
0.5
2.048
2.060
V
CC
/2
120
ns
ns
V
V
ppm/°C
kΩ
mA
mV/V
mV
Reference Output
q
(Notes 5, 6)
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Nonlinearity is defined from code 128 to code 65535 (full scale).
See Applications Information.
Note 3:
DAC switched between all 1s and code 400.
Note 4:
Digital inputs at 0V or V
CC
.
Note 5:
Reference can be overdriven (see Applications Information).
Note 6:
Guaranteed by design. Not subject to test.
3
LTC1655
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Nonlinearity
1.0
DIFFERENTIAL NONLINEARITY (LSB)
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
16,384
49,152
32,768
DIGITAL INPUT CODE
65,535
1655 G01
INTEGRAL NONLINEARITY (LSB)
1
0
–1
–2
–3
–4
–5
0
16,384
49,152
32,768
DIGITAL INPUT CODE
65,535
1655 G02
V
CC
– V
OUT
(V)
Minimum Output Voltage vs
Output Sink Current
1.0
CODE: ALL 0’s
OUTPUT PULL-DOWN VOLTAGE (V)
FULL-SCALE VOLTAGE (V)
0.8
OFFSET (mV)
0.6
125°C
0.4
25°C
0.2
–55°C
0
0
10
5
OUTPUT SINK CURRENT (mA)
Supply Current vs
Logic Input Voltage
3.4
3.0
SUPPLY CURRENT (mA)
SUPPLY CURRENT (µA)
2.6
2.2
1.8
1.4
1.0
0.6
0.2
0
1
3
4
2
LOGIC INPUT VOLTAGE (V)
5
1655 G07
4
U W
1655 F04
Integral Nonlinearity
5
4
3
2
1.0
0.8
1.2
Minimum Supply Headroom for
Full Output Swing vs Load Current
∆V
OUT
< 1LSB
V
OUT
= 4.096V
CODE: ALL 1’s
125°C
0.6
25°C
0.4
0.2
0
0
–55°C
10
5
LOAD CURRENT (mA)
15
1655 F03
Full-Scale Voltage vs
Temperature
4.10
1.0
0.8
0.6
Offset vs Temperature
4.09
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
4.08
15
4.07
–55
–25
5
35
65
TEMPERATURE (°C)
95
125
1655 G05
–1.0
–55
–10
80
35
TEMPERATURE (°C)
125
1655 G06
Supply Current vs Temperature
700
680
660
V
CC
= 5.5V
640
620
600
580
–55 –35 –15
V
CC
= 5V
V
CC
= 4.5V
5 25 45 65 85 105 125
TEMPERATURE (°C)
1655 G08
LTC1655
PIN FUNCTIONS
CLK (Pin 1):
The TTL Level Input for the Serial Interface
Clock.
D
IN
(Pin 2):
The TTL Level Input for the Serial Interface
Data. Data on the D
IN
pin is latched into the shift register
on the rising edge of the serial clock and is loaded MSB
first. The LTC1655 requires a 16-bit word.
CS/LD (Pin 3):
The TTL Level Input for the Serial Inter-
face Enable and Load Control. When CS/LD is low the
CLK signal is enabled, so the data can be clocked in.
When CS/LD is pulled high, data is loaded from the shift
register into the DAC register, updating the DAC output.
D
OUT
(Pin 4):
Output of the Shift Register. Becomes valid
on the rising edge of the serial clock and swings from GND
to V
CC
.
GND (Pin 5):
Ground.
REF (Pin 6):
Reference. Output of the internal reference is
2.048V. There is a gain of two from this pin to the output.
The reference can be overdriven from 2.2V to V
CC
/2. When
tied to V
CC
/2, the output will swing from GND to V
CC
. The
output can only swing to within its offset specification of
V
CC
(see Applications Information).
V
OUT
(Pin 7):
Deglitched Rail-to-Rail Voltage Output. V
OUT
clears to 0V on power-up.
V
CC
(Pin 8):
Positive Supply Input. 4.5V
≤
V
CC
≤
5.5V.
Requires a bypass capacitor to ground.
TI I G DIAGRA
t
9
t
7
CLK
1
D
IN
CS/LD
D
OUT
D15
PREVIOUS WORD
W
U
U
UW
U
t
1
t
2
2
t
4
t
3
3
15
16
t
6
D15
MSB
D14
D13
D1
D0
LSB
t
5
t
8
D14
PREVIOUS WORD
D13
PREVIOUS WORD
D0
PREVIOUS WORD
D15
CURRENT WORD
1655 TD
5
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